Rick,
None of the Max Force engines from 2010 to 2014 used DEF. Navistar used an EGR (exhaust gas recirculation) system to reduce nitric oxides instead of DEF. The problem with the system, other than it did not furnish adequate reduction, was that there was inadequate design and testing of system components that lead to very high maintenance and down time for the trucking industry. That is the reason for the law suits over the engine, and Navistar has lost many of them. The most expensive design flaw issues are related to EGR coolers that last only 20% of the engine design life and repeated turbo charger failures.
If you are having problems with a Navistar EGR engine, you would be well advised to take it to a Navistar (International Truck) dealer instead of a Cummins dealer. The two engines have a very different design when it comes to operating systems.
Gerald